Programmable electrical control system for a transport hoist

ABSTRACT

A work transfer apparatus movable along a row of stations and including a vertically movable hoist for raising and lowering a barrel or tray of work at selected stations. A programmable control system moves the apparatus from one station to another in a predetermined sequence and for raising or lowering the hoist at each station in the program.

United States Patent 1 Zeleney [l 1] 3,736,562 1 May 29, 1973 [54] PROGRAMMABLE ELECTRICAL CONTROL SYSTEM FOR A TRANSPORT HOIST [75] Inventor: Leo Z. Zeleney, Warren, Mich.

[73] Assignee: Ionic International, Inc., Warren,

Mich.

221 Filed; Nov. 24, 1969 21 Appl.No.: 879,353

[52] U.S. Cl. ..340/149 R, 340/172 R [51] Int. Cl. ..H04q 3/00 [58] Field of Search...'. ..318/17, 466;

[5 6] References Cited UNITED STATES PATENTS 3,200,377 8/1965 Frank ..340/l47P 3,348,108 10/1967 Donofrio ..340/l47P //0 III N2 /3 3,593,289 7/1971 Lerch ..340/147 P 1120,630 1/1938 Hallenbeck 212/132 926,884 6/1909 Libby 212/132 2,072,747 3/1937 Freese .212/132 2,980,264 4/1961 Burt ct al ..2l2/132 2,254,285 9/1941 Harris et al ..3l8/l7 X 3 ,039,029 6/1962 Spafford ..3 1 8/1 7 3,263,141 7/1966 Nicola ..3l8/16 Primary Examiner-Harold l. Pitts Attorney-Whittemore, Hulbert & Belknap 57] ABSTRACT A work transfer apparatus movable along a row of stations and including a vertically movable hoist for raising and lowering a barrel or tray of work at selected stations. A programmable control system moves the apparatus from one station to another in a predetermined sequence and for raising or lowering the hoist at each station in the program; x

18 Claims, 12 Drawing Figures PATENTEDMAYZQ ms 3.736.562

SHEEI 1 [1F 9 ATTORNEYS PATENTEU MAY 2 9 ms F'IG.4

SHEET 2 OF 9 FCIINVENTOR.

14 0 2. ZfZf/Vf) PROGRAMMABLE ELECTRICAL CONTROL SYSTEM FOR A TRANSPORT HOIST SUMMARY OF THE INVENTION quence. The present system is much more convenientand can be programmed in much less time than conventional systems utilizing punched paper tape system programming, for example. The present system requires no tape punching, tape verifying, tape threading or turn-around time.

In accordance with the embodiment of the invention specifically described hereinafter, a frame is constructed above a row of plating tanks and a hoist is mounted to travel the length of the frame. The hoist is electrically controlled by the programmable. control system of this invention and moves barrels or trays of work from tank to tank. The moves madeby. the hoist in both the horizontal and vertical directions are under the control of the program set into the control system memory. The hoist moves horizontally from one tank to the next in the program and moves vertically to raise or lower a barrel or tray with respect to the tank at each station.

ln the automatic operation of the system, the hoist movement ineach step of the program con'sists'of a horizontal movement followed by a vertical movement. The hoist moves horizontally from one station to the next in the program, starting out at slow speed, accelerating to fast speed and-continuing at fast speed past intermediate stations until it reaches the next station in the program where it decelerates and finally stops. A vertical movement follows in which a barrel or tray is either lowered into a tank at the station or lifted out of the tank. If the movement in an initial step-of the pro gram consists of a horizontal movement followed by a vertically upward movement, the next step in the cycle will consist of a horizontal movement followed by a vertically downward movement.

The system about to be described also includes a means for semi-automatic operation in which the movement of the hoist may be controlled either by a joystick on the hoist itself or by a joystick'on the main control console. The system also includes a manual system of operation.

Other features and objects of the invention will become apparent asthe description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a semi-diagrammatic elevational view of apparatus embodying my invention.

FIG. 2 is a view taken on the line 2-2 in FIG. 1.

FIG. 3 is an elevational view of a portion of the control system where the program is set in.

F IGS. 4-1 1 are views showing the electrical wiring in the control system.

Referring now more particularly to the drawings, the work transfer apparatus is diagrammatically illustrated in FIGS. 1 and 2. As there shown, a row of stations SlS 12 are provided and at each station there is a plating tank. These plating tanks may contain different baths or solutions used in a plating operation and are designated T1-Tl2.

A framework 10 has a horizontal track 12 extending above the row of tanks. The work transfer apparatus 14 comprises a carriage 16 having wheels 18 mounted on the track 12 for movement lengthwise of the track. A reversible drive motor-M mounted on the carriage is provided to move thecarriage back and forth on the track.

The work transfer apparatus also includes a depending frame 20 having vertical legs 22, extending downward along oppositesides of the now of tanks and having means for guiding thevertically movable barrel holders 24 whichhave horizontally inwardly extending members 26 for engagingunder the rims 28 of barrels or trays 30 to raise'andlower them. Cables 32 wrapped on the shaft 34 support the barrel holds 24, and a reversible motor M1 for driving the shaft 34 moves the barrel holders up and'down.

There are in-zone limit switches Z mounted on the overhead frame 10 respectively located at each of the 20 stations. Thec'arriage 16 hasa cam 36whichoperates these limit switches. The cams 36are elongated so that asthe carriage movesfrom zone to zone the cams 36 operate each limit switch in the general zone of its station, that is for a distance to either side of the center zone as the carriage moves into and out of center zone.

Center zone is defined asthe preciseposition of register of the carriage 16. withrespect to a particular. station where agbarrel is raised or lowered withrespect to the associated plating tank. The carriage 16 has a normally opencenter zonelimit switch CZ mounted on it and there is a center zone operator 3i-ateach station along the track which closes the center zone limit switch CZ when the carriage l6 isin: center zone position.

The carriage also has mountedon -it an up limit switch ULSW and a down limit" switch DLSW. These limit switches arenormally open. However, up limit switch-ULSW is-closed by the barrel holders 24 when the latter are at their; upper limit and down limit'switch DLSW isclosedby thebarrelholders 24 whenthe latter are at their. lower limit.

When the bar-rel holders. 24' are moved downwardly to deposit a barrel in a-plating tank at a particular sta- 'tion, they over-travelv or descend beneath the barrel after ithas been'deposited at the station to release'the barrel and permit-a subsequent horizontalmovement of the hoist to the nextstation in the program.

As stated; the automatic operation of the hoist in each step'of the program consists of a horizontal'movement followed by, a-vertical movement. The horizontal movement of the hoist is determined by the program set into-the program memory unit generally designated 40. This unit includes a'plurality of thumb wheels generally designated 41-55 having wipers 109-123 to which a negative 24-volt DC current is applied in sequence by a suitable stepping switch to step the program from one step to the-nextduring the-cycle of operation. The wiring in' the memory unit' includes the lines 377- and 1001-1012. Depending upon the setting of each thumb wheel its associated wire contacts a selected one of the electric wires 377 and 1001-1012.

These electric wires extend to an ROD-LOD relay, ROD standing for-right of destination and LCD standing for left. of;destination. This relay is provided from a selected wire in the memory unit. As seen in FIG. 5, the wires 377 and 1001-1012 are arranged in parallel and meeting at a summing junction 57. Each of these wires except wire 377 has a predetermined but different resistance built in. The values of the resistors are clearly indicated in the drawings. It will be understood that such values are entirely arbitrary and are selected to deliver a certain negative voltage to the summing junction 57 in each step of the cycle of operation depending upon the position of the thumb wheels. These negative voltages thus delivered to the summing junction amount to program signals which are specially related to the various stations in the movement of the hoist as will appear more clearly hereinafter.

The station limit switches are shown in FIG. 4, the stations being clearly designated by Roman numerals LIXV and each station limit switch or in-zone limit switch is designated 2. These station limit switches receive a positive 24 volt DC current and are normally open but are closed by the hoist as it passes through each of the stations. The wiring from each Z limit switch is connected in parallel by line 106 to the summing junction 57, such wiring including resistors as indicated. It will be noted that the resistors are arranged in a descending order of value from one end of the row of stations to the other. Thus at station I the resistance is 6000 ohms, at station II the resistance is 4000 ohms, and so on down to station IXV where the resistance is only 1300 ohms. It will be further noted that the resistances selected for the Z limit switches respectively correspond with the resistances in the circuits of wires 1001-1015 from the memory unit. The summing junction thus receives a positive current from the memory unit in each stage of the cycle, and a negative current from the 2 contact where the hoist happens to be. The algebraic sum of these voltages is read at the summing junction and operates the ROD-LOD relay to the hoist in the direction necessary to move to the next station in the cycle. If the resultant voltage at the summing junction is positive, the ROD-LOD relay is operated to cause movement of the hoist in one direction, and if negative, it is operated to move the hoist in the other direction. The hoist will move from stationto station until it reaches a station where the resistance at the Z limit switch is the same as the resistance in the wire delivering the memory unit signal to the summing junction so that the value of the negative voltage signal from the memory unit is the same as the positive voltage signal from the station limit switch wiring. The resultant voltage at the summing junction being zero, the hoist stops as will appear more fully hereinafter.

There is a mode selector switch MSS (FIG. 6) which may be used for switching the hoist from automatic to semi-automatic or to manual operation. The switch is shown in the automatic position in which the DC power line 303 is connected through the switch to the line 307. This puts current to one side of the reset button I RESET (FIG. 7) which must be closed prior to the initiating an automatic cycle. Obviously before initiating an automatic cycle it is necessary to move the thumb wheels 41-55 to the desired positions to cause the wipers associated with the respective thumb wheels to make contact with the selected wires 377 and 1001-1012 to determine the station to which the hoist is to move in each step of the cycle. As seen in FIG. 3, there are numbers on'the thumb wheels. These num-j bets are indicated in vertical order at one end of the memory unit in FIG. 5. In FIG. 3, one number on each thumb wheel is visible to show the station to which the hoist is to move in each step of the cycle. Thus when a wiper contacts the wire 377 it is in zero position; when it contacts wire 1001 it is in the No. 1 position and set to move the hoist to the first station; when it is in contact with wire 1002 it is in the No. 2 position and set to move the hoist to the second station, etc.

In the following description of an automatic cycle of operation it will be understood that the contacts of relays having set and reset coils are shown in the reset positions of the relays.

When the reset button is pushed, it closes the circuits to and resets the interrupt request relay IRRQ, the interrupt active relay IRAC, the fast right relay FASTR and the fast left relay FASTL, the vertical ready relay VREDY, the relays RITE and LEFT through line 361 (FIGS. 7 and 9), the vertical active relay VACTIV, and the cycle active relay CYAC. The coil on the stepping switch, designated STEP COIL, is likewise energized through the interrupter contacts 65. When cu-rent is applied, these contacts open and close and thus cause the stepping switch to advance rapidly to the home or starting position. When the stepping switch reaches its home position, the HOME contacts close in line 62 to energize the home auxiliary relay HOME-X. The HOME-X relay closes HOME-X contacts in line 63 to energize the set coil of reset relay RSET and the setting of this relay closes the reset contacts in line 64 to energize reset auxiliary relay RSX, thereby closing the RSX contacts in the circuit 65 to one side of the START button. Pushing the START button starts the automatic cycle of operation.

For the purposes of illustration, let it be assumed that the hoist is at station I in the down position. It must be down in order to start an automatic cycle because the down limit switch DLSW must be closed to energize the down limit switch auxiliary relay DLSWX (FIG. 6) and close its contacts in the START button circuit. The hoist must also be in-zone with respectto one of the stations to close its switch Z to energize the relay IZ (FIG. 9) and close its contact in the START button circuit.

Pushing the START button resets the reset relay RSET, and sets cycle active relay CYAC. Setting the relay CYAC closes thenormally open contact CYAC in line 66 and puts DC current on the line 311.

In order to start the hoist horizontally either to the right or to the left, it is necessary to energize either the slow right auxiliary relay SRX or the slow left auxiliary relay SLX and to do this the normally closed contacts FASTR and FASTL in lines 67 and 68 (FIG. 9) must be closed. The closing of these contacts occurs when the reset button is pushed to reset relays FASTR and FASTL.

Let it further be assumed that the first step in the program calls for movement of the hoist to station VIII, or in other words that the wiper of the first thumb wheel 41 for the first step in the program makes a circuit with line 1008 which has resistors totaling 3000 ohms. A negative 24 volts passed through line 1008 will produce a certain negative voltage at the summing junction 57.

Assuming at the start of the automatic cycle the hoist is at station I and therefore that the 2 limit switch at station I is closed, the positive voltage supplied to the summing junction through this Z limit switch must pass through the 6000 ohms resistor in the line. Obviously,

the positive voltage at the summing junction from the station switch will be less than thenegative voltage supplied by the program from line 1008. Accordingly, there will be a negative unbalance at the summing junction which will operate the ROD- LOD relay to close contact 70 and indicating that the hoist is initially left of its destination. Obviously if the hoist were right of its destination the resultant current at the summing junction would be a positive voltage which would operate the ROD-LOD relay in the opposite sense to close contact 72 indicating that the hoist was initially right of its destination.

Having in this instance closed contact 70, the circuit to the left of destination auxiliary relay LODX (FIG. 1 1) is closed, closing the contact LODX (FIG. 9) to the line 347 which leads to the slow right auxiliary relay SRX (FIG. 6). Obviously if the other contact 72 had been closed indicating right of destination, the circuit to the right of destination auxiliary relay RODX would have been closed to energize that relay and close the.

contact RODX leading to the circuit 349 of the slow left auxiliary relay SLX.

The circuit to the slow right auxiliary relay SRX having now been closed, contact SRX is closed to close the circuit to line 817. AC current in the line 817 energizes the low right motor starter SR (FIG. 10), closing the slow right contacts SLRT'to the slow winding of the carriage motor M to start the carriage 16 moving slowly towards the right. It will be understood at this time, the carriage still being in zone, that current on line 107 from the station in zone limit switch Z energizes the inzone relay IZ to open the normally closed contact IZD in the circuit 73 to the set coil of the fast right relay FASTR. However, during this initial slow movement of the carriage to the right, the set coil of the relay RITE is energized to close the contact RITE in line 73. Hence the relay FASTR is not yet set.

The carriage will move from the first station into a space between stations in which it is not in-zone with respect to any station. When thus between zones, the lZD relay will become de-energized to return its contacts to their normal positions. Also, the Z limit switch at station I opens to de-energize the IZ relay closing its IZ contact in line 74 (FIG. 9) to short out the summing junction57. Hence current is taken off the relay LODX to open the circuit to the slot right auxiliary relay SRX thus de-energizing the slow right motor starter coil.

When the in-zone relay [2 is thus de-energiz ed, the contact 12 in line 78 opens to de-energize relay IZD. This closes contact IZD in line 73 to energize the set coil of the fast right relay FASTR closing contact FASTR in line 79 which leads to line 348 energizing the fast right relay FRX (FIG. 6). Energization of relay F RX closes its contacts F RX to put AC current on line 818 which leads to the fast motor starter causing its contacts FASTRT to close in the fast right winding of the carriage motor to move the carriage fast to the right.

At this point it should be stated that in order to stop" the carriage at the next designated station in the cycle, it is necessary to energize theright auxiliary relay RITX in line 80. This requires the simultaneous closing of the contacts IZD and LODX in that line. It will be understood that when the carriage moves in-zone with respectto every station it passes, the IZD contact in line 80 closes while the LODX contact opens. However, the IZD relay has a delay on pulling in while the LODX relay does not, so that the LODX contacts open before the IZD contacts close. Hence no circuit is completed to relay RITEX as the carriage passes intermediate stations.

When the carriage reaches the next designated station in the cycle, in this instance station VIII, it will be obvious that, the resistors at station VIII being the same as the resistors in the first step of the program, the sum of the voltages at the summing junction will be zero and hence there will be no energization of the ROD-LOD relay and therefore no energization of the left of destination auxiliary relay LODX. Hence the LODX contact in line 80 will remain closed and when the IZD contact in that line closes upon entry of the carriage into zone 8, relay RITEX is energized to close its contacts RITEX in line 81 and energize the reset coil of the right relay RITE. This opens its contact in line 73. At the same time the fast right relay FASTR is reset to open its contact in line 79. As a result, the fast right auxiliary relay FRX is de-energized and the fast right motor starter is likewise de-energized. At the same time the decelerate right relay DECR is set to close its contact in line 82 and energize the slow right auxiliary relay SRX and in'tum operate the carriage motor on slow speed to the right. This will continue until the normally open carriage center zone limit switch C2 is operated at center zone to close the contact in line 83 and operate the reset coil of relay DECR and open its contact in line 82 to the slow right auxiliary relay SRX. The carriage will now stop at its first station.

Resetting relay DEC-R closes its contacts in line 85 to set the vertical ready relay VREDY and close its contacts in line 86 to set relay VACTIV and close its contacts in line 87 (FIG. 11) to energize time delay relay VACTIV-TD. After a predetermined interval its contacts in line 88 close. This line contains the contacts DLSWX which are normally open but are closed when the hoist is down. In the down position of the hoist it closes down limit switch DLSW (FIG. 6.) to energize down limit switch auxiliary relay DLSWX and close the contacts of the relay in line 88.

The circuit in line 88 is closed in the first step of the cycle through the wiper 91 of the stepping switch in the step 1 position shown (FIG. 11) to line 89 leading to line 351 which leads to the up auxiliary relay UX. Line 90 form the stepping switch wiper leads to a time delay switch 90'. which may connect current either to (a) the adjustable long delay relay LDLY, (b) the adjustable short delay relay SDLY, or (c) neither relay. These relays LDLY and SDLY have normally closed contacts in the line 89 and energization of either relay will immediately open its contact and causeit to close after a predetermined long or short delay. By thus introducing a time delay, if desired, the interval between the horizontal movement and the subsequent vertically upward movement of the hoist'may be controlled.

When the auxiliary relay UX is energized (FIG. 6) its contacts UX close in the line 815 to put AC current on the UP starter (FIG. 10) which closes the UP contacts in the circuit to the motor M1 causing the motor to move the hoist in an upward direction. When the hoist reaches its upper limit it engages the upper limit switch ULSW to open the circuit to the UP starter and stop the cycle. During the upward movement of the hoist the limit switch DLSW of course opens to de-energize relay DLSWX and open its contact in the line 88 which supplies current to the up auxiliary relay UX. However,

current is continued to be supplied to the relay UX through the holding circuit in line 92 of FIG. 6.

When the hoist reaches its upper limit and closes upper limit switch ULSW, up limit switch auxiliary relay ULSWX is energized to close its contacts in the line 93 (FIG. 11) to supply current through the wiper 94 of the stepping switch to the stepping auxiliary relay STEPX energizing its contacts in the line 95 to the stepping switch drive relay STEPCODR. When this relay is energized, its contacts in line 96 are closed to send current to the stepping coil of the stepping switch causing it to advance one step to step 2 in the cycle of opera tion. It will be noted that line 96' leads to a time delay switch 97 which can energize either of he adjustable time delay relays LDLY and SDLY, or neither of them, to open one of the relay contacts in the line to relay STEPX for a predetermined time, if desired, to delay the operation of the relay STEPX. Thus a delay at the end, as well as the beginning of the vertically upward hoist movement is possible.

When the stepping switch moves to the second step in the cycle, the second program signal is called in by cuit through line 201 to the step auxiliary relay STEPX to advance the stepping switch to step 3 in the program.

The movement of the hoist throughout the remaining steps in the program continues in the same manner as here-to-fore described, the first step consisting of a horizontal movement followed by a vertically upward movement of the hoist, the second step consisting of a horizontal movement followed by a vertically downward movement, and alternately in that manner throughout the remaining steps in the cycle.

In the event that the hoist in any step of the cycle should be right of destination rather than left of destination as heretofore described, it will be understood that there will be a positive imbalance at the summing l5 junction operating the ROD-LOD relay in FIG. 8 in the thumb wheel 42 to determine the next station or tank to which the hoist will move. Thus if the next station in the cycle is to b station XII for example, the program signal received at the summing junction will pass through the particular resistance in the wiring 1012 to the summing junction. At the same time, the station signal through the in-zone limit switch Z at station VIII will pass through the resistance associated with the limit switch Z to the summing junction. Again there will be a negative imbalance at the summing junction and operation of the ROD-LOD relay in FIG. 8 to close contact 70 to the LODX auxiliary relay indicating that the hoist at station VIII is left of destination. The energization of relay LODX will, as in the first step of the cycle, result in the operation first of the slow winding of motor M 1 and later of the fast winding to accelerate the hoistin a right direction to full speed through the intermediate stations and finally to decelerate and stop the hoist in center zone relation with respect to station XII which we have assumed is the second station in the cycle of automatic operation.

At the end of the horizontal movement of the hoist in the second step to station XII, there will follow a vertically downward movement of the hoist at that station. Referring to FIG. 1 1, it will be understood that the wipers 91 and 92 of the stepping switch will be in position No. 2 in this second step of the cycle so that current will now pass through line 93 through wiper 94 to line 99 and ultimately to line 352, which as seen in FIG. 6 goes to the down auxiliary relay DX. Energization of relay DX closes its contacts in line 816 to energize the down starter D and close its contacts in the circuit to the Motor M1 to lower the hoist. The contacts ULSWX in line 93 are of course closed when the hoist is in the up position by reason of the fact that the up limit switch (FIG. 6) is closed in the upper position of the hoist to energize relay ULSWX and close its contacts in line 93. While this relay becomes de-energized and its contacts in line 93 open after initial downward movement of the hoist, nevertheless, the holding circuit 100 (FIG. 6) maintains the circuit to the down auxiliary relay DX during the entire downward movement of the hoist.

When the hoist reaches its lower limit, the contacts DLSWX (FIG. 11) open because of the closing of the down limit switch DLSW by the hoist, closing the cirsuch a manner as to close contacts 72 and energize the right of destination auxiliary relay RODX in line 202 (FIG. 11). This will close the contacts RODX in line 203 to the line 349 which leads to the slow left auxiliary relay SLX (FIG. 6). The circuit to the slow left auxiliary relay SLX having been closed, contacts SLX are closed to close the circuit to line 819 (FIG. 6). AC current in line 819 energizes the slow left motor starter SL (FIG. 10) closing the slow left contacts SLLT to the slow winding of the carriage motor M to start the carriage 16 moving slowly toward the left. While the carriage is still in zone to hold closed the Z limit switch at that station, the current on line 107 from the station inzone limit switch 2 energizes the in-zone relay 12 to open the normally closed contacts IZD in the circuit 204 to the set coil of the fast left relay FASTL. However, during this initial slow movement of the carriage to the right the set coil of the relay LEFT is energized to close its contact in line 204. Hence the relay FASTL is not yet set. The carriage will move into a space between stations in which it is not in zone with respect to any station. When the carriage leaves the prior station and the Z limit switch at that station opens, the relay IZ is de-energized to close its 12 contact in line 74 to short out the summing junction 57. Hence current is 1 taken off the relay RODX to open the circuit to the slow left auxiliary relay SLX thus de-energizing the slow left motor starter coil. When the in-zone relay I2 is thus de-energized, the contact IZ in line 78 opens to de-energize relay IZD. This closes contact IZD in line 204 to energize the set coil of the fast left relay FASTL closing its contacts in line 205 which leads to line 350 energizing the fast left relay FLX (FIG. 6). Energization of relay FLX closes its contacts FLX to put AC current on line 820 which leads to the fast left motor starer FL causing its contacts FASTLT to close in the fast left winding of the carriage motor M to move the carriage fast to the left.

When the carriage reaches the next designated station in the cycle where the resistors in the program signal circuit are the same as those in the station signal circuit, the sum of the voltages at the summing junction will be zero and hence there will be no energization of the ROD-LOD relay and therefore no energization of the right of destination relay RODX. Hence the RODX contact in line 205 will remain closed and when the IZD contact in that line closes upon entry of the carriage into the next selected zone, relay LEFTX is energized to close its contacts in line 206 and energize the reset coil of the left relay LEFT to open its contacts in line 204. At the same time, the fast left relay FASTL is reset to open its contacts in line 205. As a result the fast left auxiliary relay FLX is de-energized and the fast left motor starter is likewise de-energized. At the same time, the decelerate left relay DECL is set to close its contacts in line 207 and energize the slow left auxiliary relay SLX and in turn operate the carriage motor on slow speed to the left. This will continue until the normally open carriage-center zone limit switch C2 is operated at center zone to close the contact in line 83 and operate the reset coil of relay DECL and open its contact in line 207 to the slow left auxiliary relay SLX stopping the carriage at the desired station.

Resetting relay DECL closes its contacts in line 85 to set the vertical ready relay VREDY to prepare for the subsequent vertical movement of the hoist as already described.

If in two successive steps in the cycle of operation the hoist is programmed to the same station, the hoist obviously will not more horizontally in the second of the two steps but will move at once in a vertical direction. As shown in FIG. 9A, the relay VAX is in line 260. When the stepping switch moves to the next step in a cycle, the contact STEPCODR is closed to energize relay VAX and this relay stays energized through the holding circuit provided by its contact. Relay VAX also has a contact in line 261 which closes to energize relay VX to close a contact of the latter relay in line 262. Accordingly, if at the beginning of a particular step, the hoist is already at the station it is programmed to, the summing junction 57 will indicate a zero potential and neither of the relays RODX and LODX will be energized. Hence the normally closed contacts of the latter relays in line 262 will remain closed and the set coil of relay VACTIV will be energized. Accordingly, its contact in the circuit to relay VACTlV-TD (FIG. 11) will close. The contact of the latter relay will then close to initiate the vertical movement of the hoist.

It should be understood of course that in automatic operation the hoist can move vertically only when in center zone position to close the contacts CZ in FIG. 6.

The hoist is also capable of manual operation by switching the mode selector switch MSS in'FIG. 6 to manual position. As a result, current is placed on line 310 which leads to the joy stick on the hoist. Shifting to manual also energizes the relay MANL to close its normally open contacts in FIG. 6 and open its normally closed contacts. By moving the joy stick to any of the positions up, down, right or left as indicated by the symbols UP, DN. R and L, the hoist may be moved horizontally or vertically as desired. Such vertical movement may be initiated whether or not the hoist is in center zone position with respect to any station because of the contacts MANL bypassing the center zone switch CZ.

The hoist may also be operated in the semi-automatic condition by the mode selector switch MSS in FIG. 6. Either the hoist joy stick or the console joy stick may be used in semi-automatic. The console joy stick is located in a fixed operators station and does not move with the hoist. When operating in semi-automatic with the joy stick, the current for up (UP) and down (DN) passes through lines 263 and 264. The current for horizontal movement passes through the console joy stick wiring via lines 265 and 266. Lines 265 and 266 as shown lead to lines 575 and 578 in FIG. 9 to bypass the contacts of the relays LODX and RODX to start the horizontal movement of the hoist. Up and down movement caused by the console joy stick obviously will send current to the appropriate up and down auxiliary relays DX and UX to move the hoist up or down assuming of course that it is in center zone with respect to a station. The console joy stick as stated may also be used in semi-automatic since in semi-automatic the line 309 receives current from the mode selector M88 and delivers it to the console joy stick.

When in automatic operation, the hoist may be stopped at any time by pushing the interrupt switch INTER in FIG. 7 to close the circuit to the relay IN- STIR in line 270 which opens the circuit in the AC power lines to the motors M and M1 in FIG. 10 to immediately interrupt the hoist movement. The continue button 271 is operated to de-energize the relay INSTIR to re-close the power circuit in FIG. 10 and resume operation of the hoist movement where the program was interrupted.

By switching the mode switch MS in FIG. 7 to the other position from that shown, the operation may be stopped but only at the end of any particular step in the cycle. Thus when the interrupt switch INTER is closed with the mode switch MS in the other position, the relay IRRQ is set with the result that its contact in the line 272 to the Relay IRAC is completed to set the latter relay and open its contact in line 66 thereby taking current off the line 311. However, this does not take place until the end of a step in the cycle when the contact STEPCODR in line 96 closes as described above. The cycle may be then continued by pressing the button CONT in line 275 to set-the relay CYAC and close its contact in line 66 and restore DC current to line 311.

What I claim as my invention is:

1. Work transfer apparatus movable along a row of stations, means adjacent each station for producing a station signal different from the other station signals, program means including means for producing a plurality of program signals respectively related to said station signals in a sequence of steps, means for selecting the program signal to be produced in each step, means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, means responsive to the comparing operation of said sensing means for stopping said apparatus at a particular station where the station signal is related to the program signal, and means for advancing said program means to the next step in the sequence after the stopping of said apparatus.

2. The work transfer apparatus defined in claim 1, wherein said station signals are electrical signals of one polarity and said program signals are electrical signals of the opposite polarity.

3. The work transfer apparatus defined in claim 2, wherein each station signal and related program signal are of the same value but of opposite polarity.

4. The work transfer apparatus defined in claim 3, wherein said station signals are arranged in a descending sequence along the row of stations.

5. The work transfer'apparatus defined in claim 4, wherein said sensing means is operative to render said stopping means operative when the algebraic sum of the program signal and station signal being sensed is zero.

6. The work transfer apparatus defined in claim 1, wherein said stopping means has means for decelerating said apparatus when it reaches the general zone of said particular station and for fully stopping said apparatus at the center zone thereof.

7. The work transfer apparatus defined in claim 6, wherein said moving means includes means for starting and accelerating said apparatus upon the advance of said program to the next step as aforesaid, and for moving said apparatus at full speed to the next programmed station when said apparatus leaves the general zone of the preceding station at which it was stopped.

8. Work transfer apparatus comprising a carriage movable longitudinally along a row of stations, a work support mounted on said carriage for transverse movement, means adjacent each station for producing a station signal different from the other station signals, program means including means for producing a plurality of program signals respectively related to said station signals in a sequence of steps, means for selecting the program signal to be produced in each step, means for moving said carriage along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said carriage moves therealong, means responsive to the comparing operation of said sensing means at each station for directing the movement of said apparatus toward the station where the station signal is related to said program signal and for stopping said carriage at the particular station where the station signal is related to the program signal, means responsive to the stopping of said carriage for moving said work support transversely, andmeans responsive to the completion of the transverse movement of said work support for advancing said program means to the next step in the sequence.

9. The work transfer apparatus defined in claim 8, wherein the transverse movement of said work support in each succeeding step in the sequence of steps is alternately in opposite directions.

10. The work transfer apparatus defined in claim 8, wherein said means for selecting the program signal to be produced in each step includes a separate switch for each step which is independently adjustable.

11. Work transfer apparatus movable along a row of stations, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respectively related to said station signals, said program means including separate switches for said respective step, said switches being independently adjustable to select the program signals to be produced in each of said steps, means operative in each step of said program means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, means responsive to the comparing operation of said sensing means for stopping said apparatus at the particular station where the station signal is related to the program signal, and means for advancing said program means to the next step in the sequence after the stopping of said apparatus.

12. The transfer apparatus defined in claim 11, wherein means are provided for moving said apparatus vertically in each step in the sequence after the aforesaid stopping of said apparatus.

13. The transfer apparatus defined in claim 12, wherein the vertical movement of said apparatus in each succeeding step in the sequence is alternately upward and downward.

14. The transfer apparatus defined in claim 13, wherein said signals are electrical signals and each station signal and related program signal are of the same value but opposite polarity.

15. The transfer apparatus defined in claim 14, wherein said station signals are arranged to a descending sequence along the row of stations.

16 The transfer apparatus defined in claim 13, wherein adjustable time delay means are provided in said program means effective at the beginningor end of the upward movement of the apparatus.

17. Work transfer apparatus comprising a carriage movable longitudinally along a row of stations, a work support mounted on said carriage for transverse movement, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respectively related to said station signals, said program means including separate switches for said respective steps, said switches being independently adjustable to select the program signals to be produced in each of said steps, means operative in each step of the program means for moving said carriage along said row of stations, sensing means operative in each step of the program means for sensing the program signal and the station signal at each station and comparing the same as said carriage moves therepast, means responsive to the comparing operation of said sensing means for stopping said carriage at the particular station where the station signal is related to the program signal, means responsive to the stopping of said carriage for moving said work support transversely, and means responsive to the completion of the transverse movement of said work support for advancing said program means to the next step in the sequence.

18. -Work transfer apparatus movable along a row of stations, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respec tively related to said station signals, said program means including means for selecting the program signal to be produced in each step, means operative in each step of said program means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, and means responsive to the comparing operation of said sensing means for stopping said apparatus at the particular station where the program signal is related to the station signal. 

1. Work transfer apparatus movable along a row of stations, means adjacent each station for producing a station signal different from the other station signals, program means including means for producing a plurality of program signals respectively related to said station signals in a sequence of steps, means for selecting the program signal to be produced in each step, means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, means responsive to the comparing operation of said sensing means for stopping said apparatus at a particular station where the station signal is related to the program signal, and means for advancing said program means to the next step in the sequence after the stopping of said apparatus.
 2. The work tranSfer apparatus defined in claim 1, wherein said station signals are electrical signals of one polarity and said program signals are electrical signals of the opposite polarity.
 3. The work transfer apparatus defined in claim 2, wherein each station signal and related program signal are of the same value but of opposite polarity.
 4. The work transfer apparatus defined in claim 3, wherein said station signals are arranged in a descending sequence along the row of stations.
 5. The work transfer apparatus defined in claim 4, wherein said sensing means is operative to render said stopping means operative when the algebraic sum of the program signal and station signal being sensed is zero.
 6. The work transfer apparatus defined in claim 1, wherein said stopping means has means for decelerating said apparatus when it reaches the general zone of said particular station and for fully stopping said apparatus at the center zone thereof.
 7. The work transfer apparatus defined in claim 6, wherein said moving means includes means for starting and accelerating said apparatus upon the advance of said program to the next step as aforesaid, and for moving said apparatus at full speed to the next programmed station when said apparatus leaves the general zone of the preceding station at which it was stopped.
 8. Work transfer apparatus comprising a carriage movable longitudinally along a row of stations, a work support mounted on said carriage for transverse movement, means adjacent each station for producing a station signal different from the other station signals, program means including means for producing a plurality of program signals respectively related to said station signals in a sequence of steps, means for selecting the program signal to be produced in each step, means for moving said carriage along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said carriage moves therealong, means responsive to the comparing operation of said sensing means at each station for directing the movement of said apparatus toward the station where the station signal is related to said program signal and for stopping said carriage at the particular station where the station signal is related to the program signal, means responsive to the stopping of said carriage for moving said work support transversely, and means responsive to the completion of the transverse movement of said work support for advancing said program means to the next step in the sequence.
 9. The work transfer apparatus defined in claim 8, wherein the transverse movement of said work support in each succeeding step in the sequence of steps is alternately in opposite directions.
 10. The work transfer apparatus defined in claim 8, wherein said means for selecting the program signal to be produced in each step includes a separate switch for each step which is independently adjustable.
 11. Work transfer apparatus movable along a row of stations, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respectively related to said station signals, said program means including separate switches for said respective step, said switches being independently adjustable to select the program signals to be produced in each of said steps, means operative in each step of said program means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, means responsive to the comparing operation of said sensing means for stopping said apparatus at the particular station where the station signal is related to the program signal, and means for advancing said program means to the next step in the sequence after the stopping oF said apparatus.
 12. The transfer apparatus defined in claim 11, wherein means are provided for moving said apparatus vertically in each step in the sequence after the aforesaid stopping of said apparatus.
 13. The transfer apparatus defined in claim 12, wherein the vertical movement of said apparatus in each succeeding step in the sequence is alternately upward and downward.
 14. The transfer apparatus defined in claim 13, wherein said signals are electrical signals and each station signal and related program signal are of the same value but opposite polarity.
 15. The transfer apparatus defined in claim 14, wherein said station signals are arranged to a descending sequence along the row of stations. 16 The transfer apparatus defined in claim 13, wherein adjustable time delay means are provided in said program means effective at the beginning or end of the upward movement of the apparatus.
 17. Work transfer apparatus comprising a carriage movable longitudinally along a row of stations, a work support mounted on said carriage for transverse movement, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respectively related to said station signals, said program means including separate switches for said respective steps, said switches being independently adjustable to select the program signals to be produced in each of said steps, means operative in each step of the program means for moving said carriage along said row of stations, sensing means operative in each step of the program means for sensing the program signal and the station signal at each station and comparing the same as said carriage moves therepast, means responsive to the comparing operation of said sensing means for stopping said carriage at the particular station where the station signal is related to the program signal, means responsive to the stopping of said carriage for moving said work support transversely, and means responsive to the completion of the transverse movement of said work support for advancing said program means to the next step in the sequence.
 18. Work transfer apparatus movable along a row of stations, means for producing a different station signal for each station, program means for producing in a sequence of steps a plurality of program signals respectively related to said station signals, said program means including means for selecting the program signal to be produced in each step, means operative in each step of said program means for moving said transfer apparatus along said row of stations, sensing means operative in each step of said program means for sensing the program signal and the station signal at each station and comparing the same as said apparatus moves therepast, and means responsive to the comparing operation of said sensing means for stopping said apparatus at the particular station where the program signal is related to the station signal. 